From fe709502f4ce922d9ee1e1cbebd0a3c41452406b Mon Sep 17 00:00:00 2001
From: Wiktor Garbacz <wiktorg@google.com>
Date: Thu, 5 Aug 2021 07:07:08 -0700
Subject: [PATCH] Wait for global forkserver when shutting it down

Otherwise starting forkserver multiple times will result in zombie processes lingering around.

PiperOrigin-RevId: 388926497
Change-Id: Ia9947cce3d9e909edd709b0d3525e1ae8b8bbc51
---
 sandboxed_api/sandbox2/global_forkclient.cc | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/sandboxed_api/sandbox2/global_forkclient.cc b/sandboxed_api/sandbox2/global_forkclient.cc
index 2107729..e3cec0a 100644
--- a/sandboxed_api/sandbox2/global_forkclient.cc
+++ b/sandboxed_api/sandbox2/global_forkclient.cc
@@ -19,6 +19,8 @@
 #include <fcntl.h>
 #include <sys/prctl.h>
 #include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <syscall.h>
 #include <unistd.h>
 
@@ -192,9 +194,21 @@ void GlobalForkClient::ForceStart() {
 }
 
 void GlobalForkClient::Shutdown() {
-  absl::MutexLock lock(&GlobalForkClient::instance_mutex_);
-  delete instance_;
-  instance_ = nullptr;
+  pid_t pid = -1;
+  {
+    absl::MutexLock lock(&GlobalForkClient::instance_mutex_);
+    if (instance_) {
+      pid = instance_->fork_client_.pid();
+    }
+    delete instance_;
+    instance_ = nullptr;
+  }
+  if (pid != -1) {
+    pid_t wpid = TEMP_FAILURE_RETRY(waitpid(pid, nullptr, 0));
+    if (wpid != pid) {
+      SAPI_RAW_PLOG(ERROR, "Waiting for %d failed", pid);
+    }
+  }
 }
 
 pid_t GlobalForkClient::SendRequest(const ForkRequest& request, int exec_fd,